Overlay

Object Hierarchy:

Description:

[ CCode ( type_id = "gtk_overlay_get_type ()" ) ]
public sealed class Overlay : Widget, Accessible, Buildable, ConstraintTarget

`GtkOverlay` is a container which contains a single main child, on top of which it can place “overlay” widgets.

![An example GtkOverlay](overlay.png)

The position of each overlay widget is determined by its [property@Gtk.Widget:halign] and [property@Gtk.Widget:valign] properties. E.g. a widget with both alignments set to gtk_align_start will be placed at the top left corner of the `GtkOverlay` container, whereas an overlay with halign set to gtk_align_center and valign set to gtk_align_end will be placed a the bottom edge of the `GtkOverlay`, horizontally centered. The position can be adjusted by setting the margin properties of the child to non-zero values.

More complicated placement of overlays is possible by connecting to the [signal@Gtk.Overlay:GtkOverlay:get-child-position] signal.

An overlay’s minimum and natural sizes are those of its main child. The sizes of overlay children are not considered when measuring these preferred sizes.

GtkOverlay as GtkBuildable

The `GtkOverlay` implementation of the `GtkBuildable` interface supports placing a child as an overlay by specifying “overlay” as the “type” attribute of a `<child>` element.

CSS nodes

`GtkOverlay` has a single CSS node with the name “overlay”. Overlay children whose alignments cause them to be positioned at an edge get the style classes “.left”, “.right”, “.top”, and/or “.bottom” according to their position.

Namespace: Gtk

Package: gtk4

Content:

Properties:

public Widget child { get; set; }
The main child widget.

Creation methods:

public Overlay ()
Creates a new `GtkOverlay`.

Methods:

public void add_overlay (Widget widget)
Adds widget to this.
public unowned Widget? get_child ()
Gets the child widget of this.
public bool get_clip_overlay (Widget widget)
Gets whether widget should be clipped within the parent.
public bool get_measure_overlay (Widget widget)
Gets whether widget's size is included in the measurement of this.
public void remove_overlay (Widget widget)
Removes an overlay that was added with add_overlay.
public void set_child (Widget? child)
Sets the child widget of this.
public void set_clip_overlay (Widget widget, bool clip_overlay)
Sets whether widget should be clipped within the parent.
public void set_measure_overlay (Widget widget, bool measure)
Sets whether widget is included in the measured size of this.

Signals:

public signal bool get_child_position (Widget widget, out Rectangle allocation)
Emitted to determine the position and size of any overlay child widgets.

Inherited Members:

All known members inherited from class Gtk.Widget

All known members inherited from class GLib.Object

All known members inherited from interface Gtk.Accessible

All known members inherited from interface Gtk.Buildable